In a medium skillet melt the butter over medium high heat, saute the potatoes, onions, leeks, carrots, and garlic until golden. Add the white wine and simmer for 1 minute. Add the chicken stock and simmer for 20 minutes until the vegetables are tender. Mix the flour and milk until smooth and add to the vegetables, and cook until thickened. Season, to taste, with salt and pepper. Season the chicken with salt and pepper. In a large skillet heat the oil over high heat and sear the chicken until golden. Cut seared chicken into 1/2 inch chunks and add it, the thyme, and parsley to the vegetables and set side.
For the topping: Put the potatoes in a large pot and cover with water, season with salt.
Over high heat bring to a boil and simmer until tender. Drain the potatoes and let them sit for 5 minutes to steam dry. Put the potatoes through a food mill. Warm the cream and stir into the potatoes. Mix in the butter. Season, to taste.
To assemble the pot pies fill 6 ramekins with 1 cup of filling each and top with the mashed potatoes. Bake for 30 minutes.
Place the chicken bones in a stock pot and cover with the cold water. Bring to a boil, skimming the fat and foam from the surface of the stock. Add the carrots, onions, celery, leek, parsley, thyme, bay leaves, black peppercorns, and garlic. Reduce the heat to medium low and simmer for 2 hours. Strain the stock into a container. Cool and refrigerate. Store in a tightly covered container for 5 days in the refrigerator or freeze for 1 month.